from abc import ABC, abstractmethod


class base(ABC):
    @abstractmethod
    def do_something(self):
        pass


class extendA(base):
    def do_something(self):
        print("extendA do something ---")


class extendB(base):
    def do_something(self):
        print("extendB do something +++")


a = extendA()
a.do_something()
b = extendB()
b.do_something()

""" 
extendA do something ---
extendB do something +++

"""